The present invention relates to a new and improved construction of apparatus for the application of a protective coating to the welded or soldered seam of can bodies, sometimes simply referred to herein as cans.
Generally speaking, the apparatus for applying such protective coating comprises driven rolls which are located internally of the can bodies moving past such rolls and which partially immerse in a protective coating or covering mass, typically a suitable lacquer or varnish. These applicator rolls serve for applying the protective coating or covering mass to the inner surface of the seam of the cans.
According to a prior art apparatus, for instance as disclosed in German Patent Publication No. 2,728,741, a protective covering or coating mass is applied by the circumferential or peripheral surface of a roll, immersible in the coating mass, onto the welded or soldered seam. According to another design of this prior art equipment there are provided two identical rolls arranged in series or tandem.
With the state-of-the-art apparatus it is possible to obtain a qualitatively adequate covering of the seam with the coating mass. Yet, it is difficult to optimumly accommodate the distribution of the coating mass transverse to the seam so as to take into account the momentarily prevailing requirements and conditions which are encountered when seam coating cans or the like.